YouTube musician Mike Lombardo -- a Berklee College of Music grad whose piano rock ballads and tutorials earned him 200,000 subscribers -- has been arrested by the FBI for encouraging minors to send him explicit photos and videos of themselves masturbating.

FBI Agent Alix Skelton said the investigation began after a complaint alleged Lombardo was planning to have sex with a 15-year-old girl in December 2011. The FBI spoke to two other girls, both 17, who told agents that they had exchanged sexually explicit photos and videos with Lombardo.

"All three victims advised that they 'met' Lombardo online because they were fans of his music," Skelton wrote.

According to Skelton, one victim was 14 "when she began sending nude images and videos of herself to Lombardo via Skype." Skelton said the teen said that Lombardo asked her if she "liked taking orders" and would ask the girl to "strip until she was completely nude." Once she was naked, Lombardo would allegedly direct the child to masturbate.

Lombardo has been charged on four different counts. If convicted, he could spend anywhere from five to 100 years in prison.